Device for spacing sheeting of a construction form

ABSTRACT

An arrangement for holding spaced opposite sheating boards of a construction form against movement away from each other during pouring of concrete or the like between the boards, in which an elongated metal strip extends between and with opposite ends beyond the boards. The strip is provided with a plurality of fixing holes arranged equally spaced from each other in the longitudinal direction of the strip and a plurality of elongated locking holes spaced from the fixing holes and from each other in the longitudinal direction of the strip. The arrangement includes further a first abutment means which abuts against the outer face of one of the boards and which includes a fixing member which may be a pin or a wedge driven into one of the fixing holes, whereas the second abutment means abuts against the outer face of the opposite board. The second abutment means includes a wedge driven in one of the elongated locking holes. The reference spacing of the fixing holes and that of the locking holes, the length of each locking hole and the wedge of the second abutment means are constructed and dimensioned in such a manner to assure that the opposite boards can be held against movement away from each other regardless of the desired spacing between the boards.

United States Patent [191 Maier [4 1 Aug. 7, 1973 Josef Maier, Kreuzbuehlstr. 4, D 761 1 Steinach, Germany [22] Filed: Apr. 6, 1972 [21] Appl. No.: 241,649

Related U.S. Application Data [63] Continuation-in-part of Ser. No. 8,184, Feb. 3, 1970,

[76] Inventor:

abandoned.

[30] Foreign Application Priority Data Apr. 3, 1967 Germany P 16 84 356.4 Dec. 10, 1969 Germany P 19 61 898.5

[52] U.S. Cl. 249/43, 249/213 [51] Int. Cl. E04g 17/08 [58] Field of Search 249/205, 213, 216, 249/217, 218, 40, 45, 41, 43, 214

[56] References Cited UNITED STATES PATENTS 1,907,618 5/1933 Umbach et al. 249/217 2,825,116 3/1958 Kenney 249/214 3,362,678 1/1968 Bowden 249/214 FOREIGN PATENTS OR APPLICATIONS 912,810 5/1946 France 249/43 Primary Examiner-Robert D. Baldwin Att0rneyMichael S. Striker [57] ABSTRACT An arrangement for holding spaced opposite sheating boards of a construction form against movement away from each other during pouring of concrete or the like between the boards, in which an elongated metal strip extends between and with opposite ends beyond the boards. The strip is provided with a plurality of fixing holes arranged equally spaced from each other in the longitudinal direction of the strip and a plurality of elongated locking holes spaced from the fixing holes and from each other in the longitudinal direction of the strip. The arrangement includes further a first abutment means which abuts against the outer face of one of the boards and which includes a fixing member which may be a pin or a wedge driven into one of the fixing holes, whereas the second abutment means abuts against the outer face of the opposite board. The second abutment means includes a wedge driven in one of the elongated lockingholes. The reference spacing of the fixing holes and that of the locking holes, the length of each locking hole and the wedge of the second abutment means are constructed and dimensioned in such a manner to assure that the opposite boards can be held against movement away from each other regardless of the desired spacing between the boards.

DEVICE FOR SPACING SHEETING OF A CONSTRUCTION FORM CROSS REFERENCE TO RELATED APPLICATIONS The present application is a continuation-in-part application of the copending application Ser. No. 8,184 filedFeb. 3, 1970, now abandoned.

BACKGROUND OF THE INVENTION The present invention relates to construction forms in general which confine concrete during the pouring until the concrete is hardened, and more specifically, the present invention relates to an arrangement for holding spaced and opposite sheeting boards of such a construction form against movement away from each other during pouring of concrete between the boards.

Such arrangements are known in the art and they usually include an elongated tie or tension element provided with a plurality of holes therethrough spaced from each other in the longitudinal direction of the tension element and a pair of wedges which are driven through respective holes located outside and closely adjacent to the outer faces of a pair of opposite boards, in abutment with these outer faces, so as to hold the opposite boards against movement away from each other during pouring of concrete.

These known arrangements have, however, the disadvantage that the spacing between the inner faces of the boards can be adjusted only in a stepwise manner and not to any exact desired dimension therebetween. If a certain exact dimension is required, then the arrangement needs additional means for each desired exact spacing which have to be fitted between the boards and the respective wedges, or a tie arrangement has to be used which comprises a plurality of tie members which have to be connected to each other so that the overall length of the thus obtained tie and the locationof the holes in the tie may be adjusted.

This not only increases the number of elemen which have to be provided and therefore the cost of the tie arrangement, but at the same time the assembly of such an arrangement in. situ will become complicated and time consuming.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an arrangement for holding spaced and opposite sheeting boards of a construction form against movement away from each other during pouring of concrete between the boards and which avoids the aforementioned disadvantages of such arrangements known in the art.

It is a further object of the present invention to provide for an arrangement of the aforementioned kind in which opposite sheeting boards of a construction form may be securely held against movement away from each other regardless of the exact desired spacing between the inner faces of the opposite board.

It is an additional object of the present invention to provide for such an arrangement by means of which the above results can be obtained, and which is constructed of a few simple and standard parts so that the cost of the arrangement as well as the number of parts which have to be kept in stock can be reduced.

It is also an object of the present invention to provide for such an arrangement which can be assembled with the sheeting boards in a simple and effective manner so that the assembly can be carried out with a minimum of workers and in a very short time.

With these and other objects in view, the arrangement according to the invention for holding spaced and opposite sheeting boards of a construction form against movement away from each other during pouring of concrete between the boards mainly comprises at least one elongated one-piece tension element extending be tween and with opposite ends beyond the boards and being provided with a plurality of fixing means. arranged in a row equally spaced from each other in the longitudinal direction'of the tension element and with a plurality of elongated locking holes spaced from the fixing means at the end of the row and equally spaced from each other in the aforementioned direction and each having a transverse engaging face facing towards the fixing means. The arrangement includes further first abutment means abutting against the outer face of one of the aforementioned boards and comprising a fixing member held in fixed position by a fixing means adjacentand outside one board, and second abutment means abutting against the outer face of the opposite board and comprising a wedge inserted in one of the elongated locking holes which is adjacent and at least in part outside of the opposite board. The wedge has an inclined face which engages between opposite ends thereof the aforementioned engaging face of the one locking hole at least at a point and the wedge has in a plane parallel to the tension element and passing through the aforementioned point a width effective to maintain the second abutment means in engagement with the outer face of the opposite board. This effective width will vary between a minimumeffective width and a maximum'effective width depending upon the desired spacing between the boards. In order to assure that by such an arrangement the opposite boards will be securely held against movement away from each other for any desired space between the inner faces of the opposite boards, the length ofjeach locking hole has to be smaller than the maximum width of the key and the reference spacing'of the fixing means has to be substantially equal to the reference spacing of the locking holes or a multiple thereof plus or minusa distance which is slightly longer or at least equal to (k+s)/( m-I and slightly shorter or at most equal to v, wherein k is the minimum effective width of the wedge, s is the length of the material between adjacent locking holes, m is the number of fixing holes, and v is equal to the length of each locking hole minus k.

The aforementioned fixing means may be constituted by a plurality of fixing holes and the fixing member may be constituted by a pin having a cross section to'fit with a push fit in any of the fixing holes and being inserted and thereby held in fixed position in a fixing hole outside and adjacent the one board.

Instead of a pin, the fixing member may also be constituted by a wedge which has to be driven in the corresponding fixing hole.

BRIEF DESCRIPTION OF THE DRAWING sheeting boards;

FIG. 4 is a transverse cross section through the tension element and a spacer sleeve surrounding the same;

FIG. 5a is a partial top view of a tension element having two fixing holes at the left end thereof and a plurality of locking holes;

FIG. 5b is a longitudinal section through the tension element shown in FIG. 5a with a pair of wedges respectively inserted in one of the fixing holes and in one of the locking holes;

FIG. 50 is a sectioned side view similar to that shown in FIG. 5b with the wedges inserted into different holes so as to obtain a different spacing therebetween;

FIG. 6 is a partial top view of another tension ele ment provided with three fixing holes at one end and a plurality of locking holes at the other end thereof;

FIG. 7 is a top view of a continuous band with fixing and locking holes in which the rows of fixing and locking holes are arranged in a mirror symmetrical manner, so that the band may be divided into a plurality of tension elements;

FIG. 8 is a top view of a band similar to that shown in FIG. 7 in which the fixing and locking holes are arranged mirror symmetrically with regard to a transverse center line of the band so that the band may be divided along the transverse center line into two separate tension element; and

FIG. 9 is a partially sectioned side view of part of a tension element with a locking wedge placed in position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 illustrate the arrangement of the invention for holding the sheetings 2a and 2b of a construction form for movement away from each other and to maintain a desired spacing M between the inner faces of the two sheetings during pouring of concrete 1 into the form. The sheetings 2a and 2b comprise, as usual, a plurality of sheeting boards 3, 4 and 5, 6, respectively, placed one on top of the other. The means 7 for maintaining the sheetings in the desired position spaced a distance M from each other mainly comprises an elongated one-piece substantially band shaped tension element 9 which is provided with a plurality of holes therethrough, as will be described in detail later on, and preferably also a sleeve type spacer member 8 surrounding the tension element 9 in the space between the sheetings 2a and 2b and abutting with opposite ends against the inner faces of these sheetings to prevent movement of the same towards each other. The tension element 9 projects with opposite end portion thereof between adjacent boards of each sheeting and beyond the outer faces of the same. Preferably, a pair of supporting rails 13 are provided abutting against the outer faces of the two sheetings and these rails are formed with apertures through which the opposite end portions of the tension element 9 extend. Wedges l0 and 11 are respectively inserted into holes of the tension element 9 which are respectively located outside and adjacent to the rails and the wedges are driven into the respective holes to such an extent so that the vertical faces of the wedges abut against the corresponding faces of the rails 13 and so that the inner faces of the sheetings abut against the opposite ends of the spacer sleeve 8.

As shown in FIG. 1, the holes formed in the tension element 9 are arranged in a row longitudinally spaced in the direction of the tension element from each other.

According to the invention, a plurality of fixing holes A are provided uniformly spaced from each other at one end portion of the tension element 9, which fixing holes A are followed by a plurality of elongated locking holes V which are likewise uniformly spaced from each other. As clearly shown in FIG. 6, the reference spacing a of the fixing holes A1, A2, A3 is different from the reference spacing b of the locking holes V V and V and so on for a purpose as will be described later on in detail. As shown in FIG. 6, the locking holes V are elongated holes of rectangular configuration with the long sides of the rectangle extending in the longitudinal direction of the tension member, and the fixing holes Al, A2, A3 are shown in FIG. 6 in contradistinction to the showing in FIG. 1 as substantially square holes. Instead of the wedge 10 shown in FIGS. 13 inserted in one of the fixing holes, it is also possible to use as the fixing member a pin having throughout its length a cross section corresponding to the square cross section of the fixing holes so as to fit with a push fit thereinto. The member to be inserted into any of the locking holes, however, has to be a wedge in order to obtain the above-mentioned advantages derivable from the arrangement of the invention.

The reference spacing a and b, the length of each locking hole V and the wedge 11 must be constructed and arranged in such a manner that any desired spacing between the inner faces of the sheetings 2a and 2b may be maintained. The wedge l 1 has to be driven into a selected locking hole until the inclined face of the wedge engages the transverse face of the respective locking hole which faces toward the fixing holes at at least one point while maintaining the second abutment means in engagement with the outer face of the sheeting 2a as shown in FIGS. 1 & 2. The wedge has therefore in plane parallel to the tension element passing through the contact point a width effective to maintain the second abutment means in engagement with the outer face of the sheetings 2b. The effective width of the wedge will vary between a minimum effective width, designated with the reference letter k in FIG. 9, and a maxi mum effective width designated in this Figure with the reference letter C depending upon the desired spacing between the sheeting boards. Evidently, the minimum effective width k must be slightly greater than the width at the lower end of the wedge as shown in FIG. 9 since in order to drive the wedge into the locking hole the wedge evidently needs a lead-in portion which may be shorter than that shown in FIG. 9, but evidently the minimum effective width of the wedge cannot be located at the lower end thereof.

In order to be able to steplessly adjust the distance x must be selected so that (K+l)/(m-l) X C must be greater than v+k; and

In the above formulae, is the reference spacing of the fixing holes A;

b is the reference spacing of the locking holes V;

k is the minimum effective width of the wedge, as explained above; v is the length of each elongated locking hole minus s is the length of strip material between two adjacent locking holes;

in is the number of fixing holes provided on the tension member;

n is any whole number, and preferably n=l; and C is the maximum effective width of the key.

These reference letters are indicated in FIGS. 6 and 9 and FIG. 6 show alsoreference letter s'designating the uninterrupted length of strip material between the fixing hole A, and the locking hole V, which are adjacent to each other. This length s' may be chosen in accordance with the smallest distance desired between the inner faces of the two sheeting boards. Of course, the wedge has to be constructed to be self-locking in any position and to obtain this result the inclined face of the wedge should include with the opposite face an acute angle in the order of 8 to 20".

In the following calculation and in conjunction with Table I and the drawing, especially FIGS. Sa-Sc and 6, the above-mentioned relationship is explained in further detail.

The minimum effective width k of the wedge 11 and the length s of the uninterrupted material between ad jacent locking holes are selected for reasons of strength, and for instance k may be equal to 13.2 mm and s 12 mm, and the number of fixing holes A may be selected, as shown in FIG. 6 for instance as 3, Le, m= 3. From the formula (K+s)/(ml) x g V is calculated as 12.6 mm and v which must be equal to or slightly greater than x is for instance determined with 12.8. Since the reference spacing b equals v+k+x, the reference spacing b of the locking holes will be 12.8 mm 13.2 mm 12mm =38 mm.

The reference spacing a of the fixing holes can now be figured from the formula n. b x and if n is chosen as l, the reference spacing a will become 38 mm 12.6 mm. 50.6 mm.

The distance .9 between the fixing hole A, and the adjacent locking hole V, may be, as mentioned above, arbitrarily chosen and s may be chosen as being equal to 9 mm.

TABLE I Z min A No. V No. 2 min to Z max A 1 v a s 2b 85.0 to 97.8

A3 V1 s'+2a l10.2t0123.0

220 A 1 V 4 s +3b 123.0 to 135.8 A 2 V 3 .r+a+2b 135.6 to 148.4

A 3 V2 .r'+2a+b 148.2 to 161.0

A1 V5 .r'+4b 161.0 to 173.8

225 A 2 V 4 s +a 3b 173.6 to 186.4 A 3 V 3 .1" +20 4- 217 186.2 to 199.0

A l V6 s'+5b 199.0 to 211.8

A 3 V 4 s 2n 3b 224.2 to 237.0

A l V 7 s 6b 237.0 to 249.8

230 A 2 V 6 s +1: 5b 249.6 to 262.4 A 3 V 5 s 20 4b 262.2 to 275.0

The values given in Table l are calculated under the assumption of the above-mentioned dimensions for s, s, k, a and b. Z minimum and Z maximum are indicated in FIG. 6 and the two columns A number and V number at the left hand side of the Table respectively designate the fixing hole and the locking hole in which the fixing member, respectively the locking wedge are inserted to obtain the desired spacing. Z maximum is always equal to Z minimum plus v.' Table I shows clearly that any desired spacing may be obtained in dependence in which fixing hole the fixing member is inserted and in which locking hole the wedge is driven and whether the wedge is driven into the respective locking hole to the minimum or maximum extent. In using the Table, one can also quickly establish which fixing hole and which locking hole should be used to obtain a desired spacing, for instance one may first establish the spacing between fixing hole A, and locking hole V if larger spacings Z are desired one first proceeds to the combination of fixing hole A, and locking hole V,, then to fixing hole A3 and locking hole V, and so on as indicated in Table I and as clearly shown therein it is possible to obtain any desired distance between the faces of the fixing member and the locking wedge which face each other, and therewith also any desired spacing between the inner faces of the sheetings 2a and2b.

FIGS. 5a-5c schematically illustrate another practical example of a tension element 9a and the use thereof. As shown in these Figures,-the tension element .9ais provided only with two fixing holes A, and A, and with a plurality of locking holes V,, V V and so on. The length s of the remaining material between adjacent locking holes is about half the length I of the locking holes V and the space 1, between the two fixing holes is about twice that of the distance s. The fixing holes are shown in FIG. 5a as being of rectangular configura tion with a length slightly smaller than that of the lock ing holes. In this case the fixing member 10 is preferably also constituted by awedge as shown in FIG. 5b. In use, the wedge 10 is driven always to its maximum extent into its respective fixing hole and the wedge is preferably constructed in such a manner that when thus driven into the respective fixing hole it will extend with substantially equal portions to opposite sides of the tension member 9a.

Depending on whether the fixing wedge 10 is placed into the fixing hole A, as shown in FIG. 5b or into the fixing hole A, as shown in FIG. 5c, the tension member 9a will be placed in a different position as indicated in FIGS. 5b and 5c, provided that the vertical face of the wedge 10 engages either directly the sheeting 2a (not shown in FIGS. 5a-5c) or the outer face of the rail 13 placed between this wedge and the outer face of the sheeting and when the sheeting 2a: is held in a fixedposition. It will be also evident from FIGS. 5b and 5c that the spacing between the inner faces of the wedges l0 and 11 may be steplessly adjusted between a minimum and maximum distance depending on whether the wedge l l is placed in the locking hole V, or the locking hole V, and depending on whether the wedge is driven into the respective locking hole to the minimum or to the maximum effective width thereof.

Table II hereinafter, shows the influence of the number of fixing holes A on the reference spacing a and b as well as on the length of the locking holes V. In Table II the dimension s and k are chosen identically with the dimensions as used in Table 1, that is s is equal to 12 mm and k is equal to 13.2 mm., whereas the number m of the fixing holes is varied in the four different columns of Table 11 from 2-5. The dimension x is assumed to be equal to v whereby the small overlaps of Z minimum and Z maximum, as indicated in Table l, are avoided. The various values given in Table 11 are calculated from the formulae given in connection with Table 1.

TABLE 11 m 2 3 4 5 325 s 12.0 mm 12.0 mm 13.2 mm 13.2mm k 13.2 mm 13.2 mm 13.2 mm 13.2mm x= v 25.2 mm 12.6 mm 8.4 mm 6.2mm b 50.4 mm 37.8 mm 33.6 mm 31.4mm a 75.6 mm 50.4 mm 42.0 mm 37.6mm

From Table 11 it can be ascertained that when s and k are maintained constant while m is increasing, the length v and thus the reference spacings a and b become shorter. Since with the greater number m of fixing holes, the tension element becomes more complicated to handle in practice, optimum conditions will result for m=24, and especially when m=3.

For a tension member provided with three fixing holes the following dimension ranges have proved advantageous in practice:

k about 13.2 to mm s about 12 to 13 mm v about 12.6 to 14 mm b about 38 to 42 mm a about 50 to 56 mm As shown in FIG. 7, the tension elements 9 may be made from a continuous strip B of metal, for instance steel having alternating continuous rows of fixing and locking holes arranged mirror symmetrically with respect to each other so that the user may cut from this continuous strip a length suitable for the respective thickness of the concrete wall to be cast between the sheetings. As shown in FIG. 7 the strip B is provided at its left-hand portion with a plurality of locking holes V --V which are followed by three additional fixing holes A,-A which in turn are followed by three additional fixing holes A -A and then by a group of locking holes V,V and so on, so that tension elements 9 and 9 may be cut from the strip B by severing the strip along the dash-dotted lines T and T'. If, however, somewhat shorter or somewhat longer tension elements 9 are needed, the separating line T between two adjacent locking holes V may be shifted by one or more locking hole spacings so that a shorter and a longer tension element 9 may be obtained. Evidently it is also possible with such a strip as illustrated in FIG. 7 to cut therefrom tension elements which have only two fixing holes and a desired number of locking holes. The continuous strip as shown in FIG. 7 greatly facilitates stock keeping since tension elements of various lengths and with a desired number of fixing holes and locking holes may be easily cut from the strip.

Likewise, the strip B, shown in FIG. 8 greatly facilitates stock keeping. The strip B, shown in FIG. 8 may be used for forming two tension elements 9 by cutting the strip along the transverse line T shown in dashdotted lines in FIG. 8, whereby two tension elements of equal lengths will be obtained, and of course the strip B, may be also cut along a transverse line shifted towards the right or to the left of the line T shown in FIG.

8 to produce two tension elements of different lengths and each having a different number of locking holes.

As already mentioned in connection with FIGS. 1-4, the arrangement preferably includes also a spacer sleeve 8 surrounding the tension element 9 between the sheetings 2a and 2b abutting with opposite ends thereof against the inner faces of these two sheetings. This spacer sleeve is preferably left in the concrete after the same has hardened, while the tension element 9 may be withdrawn from the interior of the sleeve. The sleeve forms in this case a reinforcement of the concrete and the sleeve is preferably provided with longitudinal extending ridges 30 and/or 31 as indicated in FIG. 4 to increase the binding surface of this spacer sleeve. Of course, other spacers, well known in the art, may also be provided between the sheetings 2a and 2b to prevent the same to move toward each other before the concrete is poured therebetween.

As likewise mentioned before, and as shown in FIGS. 1-3, a rail 13 of preferably U-shaped cross section may be sandwiched between the fixing member or fixing wedge 10 and the outer face of the sheeting 2a as well as between the locking wedge 11 and the outer face of the sheeting 2b. Evidently, the distance, M differs from the distance Z between the vertical faces of the wedges l0 and 11 by the thickness of the sheetings and the thickness of the web 13' of the supporting rails 13 which must be taken in account in selecting the fixing holes and locking holes as described above in connectionwith FIGS. 50-50 and 6. i

The arrangement according to the present invention not only provides for the above-described advantages resulting from the possibility of steplessly selecting the length M of the distance between the sheetings, but it also simplifies the installation of the construction form. Thus, the end of the tension element 9 provided with fixing holes A may be slipped through sheeting 2a, at a joint between two sheeting boards 5 and 6 and, if.a supporting rail is provided also through an appropriate opening in this rail abutting against the outer face of the sheeting 2a, whereafter a fixing member in the form of a straight pin or a fixing wedge 10 may be, inserted into a respective fixing hole located closely adjacent and outside of the rail 13. This wedge 10 may be driven into the respective fixing hole until it becomes properly engaged therein, for instance 20 that it completely fills with a portion thereof the selected fixing hole. The tension element is thus fixed in position by the wedge 10, sheeting 2a and the supporting rail 13 if such a supporting rail is provided, so that, as a rule, no further work has to be carried out on this side of the construction form. A spacer sleeve of appropriate length is then placed on the portion of the tension member 9 projecting inwardly from the sheeting 2a, whereafter the sheeting 2b is placed in abutment with the other end of the spacer sleeve 8, a supporting rail 13 is then placed in abutment with the outer face of the sheeting 2b, whereafter the locking wedge l 1 is driven in the appropriate locking hole. 1f the fixing hole is correctly selected the wedge 11 may be driven into the appropriate locking hole to a greater or smaller extent so as to keep the inner face of the sheeting 2b in abutment against the appropriate end of the spacer sleeve 8, whereby the arrangement will assure that during pouring of concrete between the sheetings, the latter may not move away from each other.

The correct fixing hole will be readily selected on the basis of experience or by eye.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of arrangements for holding spaced and opposite sheeting boards of a construction form against movement away from each other during pouring of concrete between the boards differing from the types described above.

While the invention has been illustrated and described as embodied in an arrangement for holding spaced and opposite sheeting boards of a construction form against movement away from each other during pouring of concrete between the boards and in which the spacing between inner faces of the sheetings may be selected at any desired distance, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analyses, the foregoing will so fully reveal the gist of the present invention that others can be applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended 1. An arrangement for holding spaced and opposite sheeting boards of a construction form against movement away from each other during pouring of concrete between said boards, said arrangement comprising at least one elongated one-piece tension element extending between and with opposite ends beyond said boards and being provided with a plurality of fixing means arranged in a row equally spaced from each other in the longitudinal direction of said tension element and with a plurality of elongated locking holes spaced from the fixing means at the end of the row and equally spaced from each other in said direction and each having a transverse engaging face facing toward said fixing means; first abutment means abutting against the outer face of one of said boards and comprising a fixing member held in fixed position by a fixing means adjacent and outside said one board; second abutment means abutting against the outer face of the opposite board and comprising a wedge inserted in one of said elongated locking holes which is adjacent and at least in part outside of said opposite board, said wedge having a face facing the outer face of said opposite board and an opposite face inclined at an acute angle thereto, said inclined face engaging between opposite ends of said wedge said engaging face of said one locking hole at least at one point and said wedge having in a plane parallel to said tension element and passing through said point a width effective to maintain said second abutment means in engagement with said outer face of said opposite board, said effective width varying between a minimum effective width and a maximum effective width depending on the desired spacing between said boards, the length of each locking hole being smaller than the maximum width of said wedge and the reference spacing of the fixing means being substantially equal to the reference spacing of the locking holes or a multiple thereof plus or minus a distance which is slightly longer or at least equal to (k+s)/(m-l) and slightly shorter or at most equal to v, wherein k is the minimum effective width of the wedge, s is the length of material between adjacent locking holes, m is the number of fixing holes, and v is equal to the length of each locking hole minus k.

2. An arrangement as defined in claim 1, wherein said plurality of fixing means comprises a plurality of fixing holes, said fixing member being held in a fixed position by being inserted in a fixing hole outside and adjacent said one board.

3. An arrangement as defined in claim 2, wherein said fixing means is also a wedge.

4. An arrangement as defined in claim 1, wherein said first and second abutment means further comprise supporting rails respectively sandwiched between said fixing member and said one board, and said wedge and said other board.

5. An arrangement as defined in claim 2, wherein said first and second abutment means further comprise supporting rails respectively sandwiched between said fixing member and said one board, and said wedge and said other board.

6. An arrangement as defined in claim 5, wherein at least three fixing holes and a number of locking holes greater than three are provided in :said tension element.

7. An arrangement as defined in claim 5, wherein s equals 12-13 mm., k equals 13.2-15 mm., v equals 12.8-14 mm. and b equals 38 mm. and a 505-52 mm.

8. An arrangement as defined in claim 1, wherein said fixing means and said locking holes are arranged mirror symmetrically with regard to transverse center line of said elongated tension element.

9. An arrangement as defined in claim 1, wherein said tension element consists of a flat metal strip.

10. An arrangement as defined in claim 1, and including a tubular spacer member abutting with opposite ends thereof against faces of said boards which face each other, said tubular spacer member surrounding that portion of said elongated tension element which is located between said faces. 

1. An arrangement for holding spaced and opposite sheeting boards of a construction form against movement away from each other during pouring of concrete between said boards, said arrangement comprising at least one elongated one-piece tension element extending between and with opposite ends beyond said boards and being provided with a plurality of fixing means arranged in a row equally spaced from each other in the longitudinal direction of said tension element and with a plurality of elongated locking holes spaced from the fixing means at the end of the row and equally spaced from each other in said direction and each having a transverse engaging face facing toward said fixing means; first abutment means abutting against the outer face of one of said boards and comprising a fixing member held in fixed position by a fixing means adjacent and outside said one board; second abutment means abutting against the outer face of the opposite board and comprising a wedge inserted in one of said elongated locking holes which is adjacent and at least in part outside of said opposite board, said wedge having a face facing the outer face of said opposite board and an opposite face inclined at an acute angle thereto, said inclined face engaging between opposite ends of said wedge said engaging face of said one locking hole at least at one point and said wedge having in a plane parallel to said tension element and passing through said point a width effective to maintain said second abutment means in engagement with said outer face of said opposite board, said effective width varying between a minimum effective width and a maximum effective width depending on the desired spacing between said boards, the length of each locking hole being smaller than the maximum width of said wedge and the reference spacing of the fixing means being substantially equal to the reference spacing of the locking holes or a multiple thereof plus or minus a distance which is slightly longer or at least equal to (k+s)/(m-l) and slightly shorter or at most equal to v, wherein k is the minimum effective width of the wedge, s is the length of material between adjacent locking holes, m is the number of fixing holes, and v is equal to the length of each locking hole minus k.
 2. An arrangement as defined in claim 1, wherein said plurality of fixing means comprises a plurality of fixing holes, said fixing member being held in a fixed position by being inserted in a fixing hole outside and adjacent said one board.
 3. An arrangement as defined in claim 2, wherein said fixing means is also a wedge.
 4. An arrangement as defined in claim 1, wherein said first and second abutment means further comprise supporting rails respectively sandwiched between said fixing member and said one board, and said wedge and said other board.
 5. An arrangement as defined in claim 2, wherein said first and second abutment means further comprise supporting rails respectively sandwiched between said fixing member and said one board, and said wedge and said other board.
 6. An arrangement as defined in claim 5, wherein at least three fixing holes and a number of locking holes greater than three are provided in said tension element.
 7. An arrangement as defined in claim 5, wherein s equals 12-13 mm., k equals 13.2-15 mm., v equals 12.8-14 mm. and b equals 38 mm. and a 50.5-52 mm.
 8. An arrangement as defined in claim 1, wherein said fixing means and said locking holes are arranged mirror symmetrically with regard to transverse center line of said elongated tension element.
 9. An arrangement as defined in claim 1, wherein said tension element consists of a flat metal strip.
 10. An arrangement as defined in claim 1, and including a tubular spacer member abuTting with opposite ends thereof against faces of said boards which face each other, said tubular spacer member surrounding that portion of said elongated tension element which is located between said faces. 